参考答案：

Part Ⅱ Reading Comprehension
21. D22. A23. B24. C25. D26. A27. B28. C29. D30. C
31. B32. A33. C34. C35. D36. B37. D38. C39. A40. B
 Part Ⅲ Vocabulary
41. A42. A43. D44. B45. B46. D47. C48. A49. C50. D 
51. B52. C53. A54. B55. D56. A57. C58. B59. B60. A
61. C62. D63. A64. D65. B66. C67. C68. A69. B70. D
 Part Ⅳ Error Correction
S1. only∧→doesS2.not ∧→beenS3. are →isS4. and→but
S5. are→isS6. With→WithoutS7. it→theyS8. ∧world→the
S9. shows→showingS10. not→/

Part Ⅴ Writing
The Problem of Ageing Population in China
The problem of ageing population is troubling many countries, especially the developed countries. China will soon be on the threshold of ageing population. Some cities, like Shanghai, Guangzhou, are already on the list. From the statistics given by the above table, China’s population will approach 410 million in 2050, with the growing population up to 27.4%, which means one in four people will be old citizens.
The ageing problem is bringing a series of social problems to China. First, many families in China consist of father, mother and one child. The only child has to care for the old parents in two families after he/she gets married. With the present inadequate social security system, this will present a grave problem to the old population. Second, the ageing process will inevitably result in the shortage of labor, which in turn will affect national economy.
What should we do to deal with the forthcoming problem? No doubt, building up the economic power of our country is the priority. Only when we have powerful economic foundation, can we care for the welfare of the huge ageing population. Besides, the only—child policy should be adjusted at a proper stage so as to keep a sensible percentage of the youth. In this way, the problem of ageing population can be relieved to some extent.